1. Field of the invention
The present invention relates to an ophthalmic surgical blade having hard single bevel edges.
2. Description of related art
Performance of eye surgery using an ophthalmic surgical blade has become commonplace. Numerous diverse blade designs are employed in such surgeries and each blade has its advantages and disadvantages.
During the performance of eye surgery, several problems arise caused by various features of prior art blades. For example, it is important to create a geodesic incision through the cornea at the proper angle and with the required pressure to facilitate self sealing characteristics of the wound. It is desirable, when making such an incision, to avoid deformation of eye tissues and to prevent inadvertent tearing or widening of the extremities of the incision such as are caused by sharp or squared sides on the width of the blade. Additionally, a blade should be able to create a self-sealing wound such as would be created when individual corneal layers are gradiently cut rather than slashed by the blade. A contoured cut properly aligns itself while a straight slash cut does not do so.
Known related art includes U.S. Pat. No. 5,217,476 to Wishinsky which discloses a surgical knife blade and method of performing cataract surgery utilizing a surgical knife blade. While embodiments of the Wishinsky knife blade, particularly those shown in FIGS. 1-5, are symmetrical, the present invention distinguishes from the teachings of Wishinsky as contemplating a blade wherein the lateral surfaces thereof are unsharpened and merely act as guide means.
U.S. Pat. No. 5,222,967 to Casebeer et al. discloses a keratorefractive diamond blade and surgical method wherein the blade is asymmetrical about a central longitudinal axis. The same may be said for U.S. Pat. No. 5,423,840, also to Casebeer et al. The present invention differs from the teachings of these patents as contemplating an ophthalmic blade that is symmetrical about a central longitudinal axis and has side surfaces that are not sharpened but, rather, merely function as guide means.
U.S. Pat. No. 5,352,233 to Anis discloses a scalpel and technique for using a scalpel including one embodiment showing a blade that is symmetrical about a longitudinal axis of elongation thereof. This embodiment shows sharp corners at the widest portions of the blade and a blade edge that is equidistant from the top and bottom surfaces of the blade. The present invention differs from the teachings of Anis as having side edges that are not sharpened and that merely perform a guiding function as well as a sharpened edge that is not equidistant from the top and bottom surfaces of the blade.
Other known related art includes U.S. Pat. No. 5,370,652 to Kellan which discloses a surgical knife blade for making sutureless incisions in the eye and methods therefor. The blades of Kellan are symmetrical with respect to a longitudinal axis of elongation thereof. In one embodiment, the blade edge includes a sharpened central point and side edges that are sharp as well. Other embodiments include curved cutting surfaces wherein a central point is not included. In each embodiment, the cutting edge is in a plane common with the bottom surface of the blade. The present invention differs from the teachings of Kellan as contemplating a blade symmetrical with respect to a longitudinal axis of elongation thereof having a central point, side edges that are not sharpened and merely provide guiding surfaces, and wherein the cutting edge is not equidistantly located between the top and bottom surfaces of the blade and is not in any plane common with either of those surfaces.
U.S. Pat. No. 5,376,099 to Ellis et al. discloses an undercut diamond surgical blade and method of using same. Embodiments of Ellis et al. include cutting surfaces on a blade sidewall and a cutting edge equidistantly spaced between the top and bottom surfaces thereof. In contrast, the present invention contemplates a blade having a pointed end aligned with an axis of elongation thereof with side edges unsharpened and comprising guide means and with the cutting, edge being non-equidistantly spaced between the top and bottom surfaces thereof.